Combustion Of Carbon Monoxide Research Articles

A 15-year record of CO emissions constrained by MOPITT CO observations

Abstract. Long-term measurements from satellites and surface stations have demonstrated a decreasing trend of tropospheric carbon monoxide (CO) in the Northern Hemisphere over the past decade. Likely explanations for this decrease include changes in anthropogenic, fires, and/or biogenic emissions or changes in the primary chemical sink hydroxyl radical (OH). Using remotely sensed CO measurements from the Measurement of Pollution in the Troposphere (MOPITT) satellite instrument, in situ methyl chloroform (MCF) measurements from the World Data Centre for Greenhouse Gases (WDCGG) and the adjoint of the GEOS-Chem model, we estimate the change in global CO emissions from 2001 to 2015. We show that the loss rate of MCF varied by 0.2 % in the past 15 years, indicating that changes in global OH distributions do not explain the recent decrease in CO. Our two-step inversion approach for estimating CO emissions is intended to mitigate the effect of bias errors in the MOPITT data as well as model errors in transport and chemistry, which are the primary factors contributing to the uncertainties when quantifying CO emissions using these remotely sensed data. Our results confirm that the decreasing trend of tropospheric CO in the Northern Hemisphere is due to decreasing CO emissions from anthropogenic and biomass burning sources. In particular, we find decreasing CO emissions from the United States and China in the past 15 years, and unchanged anthropogenic CO emissions from Europe since 2008. We find decreasing trends of biomass burning CO emissions from boreal North America, boreal Asia and South America, but little change over Africa. In contrast to prior results, we find that a positive trend in CO emissions is likely for India and southeast Asia.

Pharmacological Correction of Hypoxic Conditions by Complexes of Zinc with N-Alkenylimidazoles

The discovery and development of effective antihypoxic drugs is an important issue in modern experimental and clinical pharmacology. Complexes of zinc containing imidazole cycles as ligands are promising candidates for the design of novel drugs, including pharmacotherapeutic tools for patient’s protection under conditions of oxygen deficiency. Herein, we report antihypoxic activity of zinc complexes with N-alkenylimidazoles, and, specifically, a novel drug Acyzol, which can be used as efficient antidote after poisoning by carbon monoxide and other combustion products.

Evaluation of platinum catalysts for naval submarine pollution control

Catalytic air purification systems are required to maintain desirable levels of contaminants in confined space pollution control applications, such as onboard naval submarines. These systems execute oxygen generation, CO2 removal, and burning of contaminants such as carbon monoxide (CO), and hydrocarbons. Crucial characteristics of the catalytic burners on submarines include high activity toward CO combustion, long-term stability in humid environments, and minimal activity towards the decomposition of trace halogenated compounds (often used as refrigerants) that can form toxic acid gas compounds. Here, we compare currently used hopcalite/LiOH catalysts to platinum (Pt) based catalysts deposited on Al2O3 and CeO2 supports for CO combustion, tolerance to humid environments and combustion of model refrigerant contaminant molecules, freon 134a and methyl chloride. The three catalysts exhibit complete combustion of CO in dry air streams by 110°C, and no catalyst was found to activate freon 134a up to 400°C. Pt/Al2O3 and Pt/CeO2 catalysts outperformed hopcalite/LiOH by showing enhanced CO oxidation reactivity in the presence of humidity (hopcalite/LiOH is strongly deactivated when H2O is co-fed), and they are minimally active towards methyl chloride oxidation up to 275°C, whereas hopcalite/LiOH is active below 200°C. Pt/CeO2 exhibited higher reactivity for CO oxidation and lower activity for methyl chloride oxidation, as compared to Pt/Al2O3. The results strongly suggest that Pt based catalysts, similar to those used in automotive catalysis, may be excellent replacements for currently utilized hopcalite/LiOH catalysts in naval submarine pollution control applications.

Self-sustained catalytic combustion of carbon monoxide ignited by dielectric barrier discharge

This paper presents the results of a study of self-sustained catalytic combustion of CO ignited by dielectric barrier discharge (DBD) using Ce0.5Zr0.5Oy/TiO2 (CeZr/Ti), CuZr0.25Oy/TiO2 (CuZr/Ti), and CuCe0.75Zr0.25Oy/TiO2 (CuCeZr/Ti) catalysts. DBD excites and dissociates some of the reactant molecules in the gas phase. These are more easily adsorbed on the catalyst surface than are ground-state species, therefore induction begins at a lower background temperature than in thermal catalysis. CO is adsorbed on copper sites, therefore CeZr/Ti is inactive in CO ignition, but CuZr/Ti and CuCeZr/Ti achieve DBD ignition at 34 and 44s, respectively, at a specific energy density (SED) of 1500J/L. CO catalytic ignition by DBD involves two steps. The induction process is dominated by plasma catalysis. At the same SEDs, induction with CuCeZr/Ti begins earlier than those with CuZr/Ti, in good agreement with the reducibilities and oxygen-transfer properties of these catalysts. The ignition process is governed by thermal catalysis because the enhancement of external diffusion induced by increasing the temperature improves the reaction rate. CuZr/Ti provided more CO adsorption sites than did CuCeZr/Ti, contributing to shortening of the ignition delay.

Burning carbon monoxide in the settling chamber of a hotshot wind tunnel for obtaining the CO2 test gas

A method of formation and heating of CO2 as a test gas in the settling chamber of a hotshot wind tunnel is considered. To form and heat CO2, the chamber is filled with a source gas mixture of CO, O2, and CO2, and after initiation, these substances participate in an exothermic chemical reaction in accordance with the formula CO + 0.5 O2 + xCO2 = (1 + x)CO2. A stoichiometric ratio of the concentrations of carbon monoxide CO and oxygen is used. Variation of the number of moles x of ballast CO2 in the left part of the chemical formula allows changing the temperature of the resultant test gas in a wide range. Experiments in the IT-302M hotshot wind tunnel carried out at ITAM SB RAS have shown that a pressure increase during an isochoric process in the settling chamber due to the joint effect of heat released in the reaction CO + 0.5 O2 and an electric charge provides the completeness of CO combustion almost equal to unity. The time of reaction completion at its initiation by an electric arc is no more than several milliseconds.

N-heptane 연료 혼합비에 따른 n-butanol 연료의 연소 특성

ABSTRACTThis study was performed to provide the information of the combustion characteristics of n-butanol fuel in accordance with the n-heptane fuel mixing ratio. The closed homogeneous reactor model was used for the analysis. The analysis conditions were set to 800 K of the initial temperature, 20 atm of initial pressure and 1.0 of equivalence ratio. The results of analysis were compared in terms of combustion temperature, combus-tion pressure, CO, Soot and NO X emissions. The results of combustion and exhaust emission characteristics showed that ignition delay was decreased and the combustion temperature was increased as the n-heptane mixing ratio was increased. Also, the carbon monoxide(CO) was slightly decreased however, the soot and nitrogen oxides(NO X ) increased a little in accordance with the n-heptane fuel mixing ratio. In addition, the pressure difference was almost the same in any conditions. Key Words : Combustion temperature, Ignition delay, Mixture ratio, Nitrogen oxides (NO

Effect of zinc oxide on properties of phenolic foams/halogen‐free flame retardant system

ABSTRACTA halogen‐free flame retardant system consisting of ammonium polyphosphate (APP) as an acid source, blowing agent, pentaerythritol (PER) as a carbonific agent and zinc oxide (ZnO) as a synergistic agent, was used in this work to enhance flame retardancy of phenolic foams. ZnO was incorporated into flame retardant formulation at different concentrations to investigate the flammability of flame retardant composite phenolic foams (FRCPFs). The synergistic effects of ZnO on FRCPFs were evaluated by limited oxygen index (LOI), thermogravimetric analysis (TGA), cone calorimeter tests, and images of residues. Results showed that the flame retardant significantly increased the LOI of FRCPFs. Compared with PF, heat release rate (HRR), total heat release (THR), effective heat of combustion (EHC), production or yield of carbon monoxide (COP or COY) and Oxygen consumption (O2C) of FRCPFs all remarkably decreased. However specific extinction area (SEA) and total smoke release (TSR) significantly increased, which agreed with the gas‐phase flame retardancy mechanism of the flame retardant system. The results indicated that FRCPFs have excellent fire‐retardant performance and less smoke release. And the bending and compression strength were decreased gradually with the increase of ZnO. The comprehensive properties of FRCPFs were better when the amount of ZnO was 1∼1.5%. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42730.

Effect of Cetane Improver on Combustion and Emission Characteristics of Coal-Derived Sasol Isomerized Paraffinic Kerosene in a Single Cylinder Diesel Engine

Sasol isomerized paraffinic kerosene (IPK) is a coal-derived synthetic fuel under consideration as a blending stock with JP-8 for use in military ground vehicles. Since Sasol IPK is a low ignition quality fuel with derived cetane number (DCN) of 31, there is a need to improve its ignition quality. This paper investigates the effect of adding different amounts of Lubrizol 8090 cetane improver to Sasol IPK on increasing its DCN. The experimental investigation was conducted in a single cylinder research type diesel engine. The engine is equipped with a common rail injection system and an open engine control unit. Experiments covered different injection pressures and intake air temperatures. Analysis of test results was made to determine the effect of cetane improver percentage in the coal-derived Sasol IPK blend on auto-ignition, combustion and emissions of carbon monoxide (CO), total unburned hydrocarbon (HC), oxides of nitrogen (NOx), and particulate matter (PM). In addition, the effect of cetane improver on the apparent activation energy of the global auto-ignition reactions was determined.

Structural analysis of combustion mechanisms

Thirty-nine detailed mechanisms for combustion of hydrogen, carbon monoxide and methanol are investigated using ReactionKinetics, a Mathematica based package published earlier. Our methods involved mainly structural and graph theoretical approaches as well as techniques which are related to the time evolution of the considered mechanisms. Our investigations support the view that the hydrogen mechanisms tend to take on a final form in these days. CO combustion mechanisms, however, showed a larger variety both in species and in reaction steps. There exist only a few mechanisms directly developed to describe methanol combustion (mechanisms developed for other purposes may contain a submechanism for methanol combustion); the big differences between them shows that the modeling community is only at the very beginning of exploring this process. Most of our results do not depend on the choice of reaction rate coefficients, the methods only use the underlying sets of reaction steps, hence they are robust and general. These investigations can be used before or in parallel with usual numerical investigations, such as pathway analysis, sensitivity analysis, parameter estimation or simulation. The package and the methods may be useful for automatic mechanism generations, testing, comparing and reduction of mechanisms as well, especially in the case of large systems.

Self-sustained combustion of carbon monoxide promoted by the Cu-Ce/ZSM-5 catalyst in CO/O2/N2 atmosphere

The Cu/ZSM-5, Ce/ZSM-5 and Cu-Ce/ZSM-5 catalysts were prepared and characterized in this investigation and the catalytic activity of carbon monoxide (CO) combustion under these catalysts was determined by temperature-programmed oxidation. The activity for the CO combustion follows the decreasing order: Cu-Ce/ZSM-5>Cu/ZSM-5>Ce/ZSM-5, indicated by lower ignition, light-off, extinction temperature and broader hysteresis determined via both heating and cooling feeding process. The CO adsorbed on the copper sites to form Cu+–CO complexes, monodentate and bidentate carbonates was considered to be the crucial step for CO catalytic combustion. At the CO concentration ≥5vol.%, the CO self-sustained combustion was achieved over the Cu-Ce/ZSM-5 catalyst. One reason is due to formation of Cu2+ ions incorporated into cerium oxides, which are more reducible than the copper clusters, minicrystals and bulk CuO particles. Another reason is attributable to the formation of Ce4+/Ce3+ redox couple, which facilitates oxygen transport on the catalyst surface.

Catalysts for selective propane oxidation in the presence of carbon monoxide: Mechanistic aspects

The competitive combustion of propane and carbon monoxide was investigated with regard to its selectivity for propane oxidation. Based on variations in the sol–gel synthesis and the composition, the TiCrOx catalysts were optimized. Specifically, the addition of small amounts of cerium led to a catalyst, which converted 89% propane at 375°C but no carbon monoxide. The origin of this excellent and unusual selectivity has been investigated. The method of choice was diffuse reflectance infrared Fourier transformed spectroscopy (DRIFTS), which allowed recording adsorbed species on the catalysts surface. Hopcalite was taken as reference catalyst due to its selectivity (although opposite to TiCrOx) for the combustion of carbon monoxide in the presence of hydrocarbons. The spectroscopic investigations showed that carbon monoxide is linearly adsorbed on Cu+ at lower temperatures and formed carbonates at higher temperatures, whereas propane formed no detectable adsorbed species on hopcalite. The TiCrOx catalyst formed formate species with carbon monoxide above 250°C and carboxylates with propane above 150°C. The mixture of propane and carbon monoxide led to the formation of both species. By the addition of oxygen to the gas feed, only propane formed adsorbates on the catalysts surface, whereas CO seemed not to interact with the surface. Pre-adsorbed oxygen probably inhibits the adsorption of carbon monoxide but is not necessary for propane activation. The formation of carboxylates from propane also takes place in the absence of molecular oxygen, pointing to a Mars-van-Krevelen-like mechanism, in which lattice oxygen is involved in the oxidation process. A physical mixture of TiO2 and Cr2O3 showed no catalytic activity, and spectroscopic investigations showed no adsorbates on the sole oxides. Since only anatase and eskolaite could be identified in the powder diffraction patterns of the catalysts, a third phase has to be responsible for the propane oxidation, most likely surface decorations or solid solutions of the metal ions.

Grey-box modeling of HCCI engines

Homogenous Charge Compression Ignition (HCCI) holds promise to increase indicated thermal efficiency and reduce Nitrogen Oxides (NOx) and Particulate Matter (PM) emissions from internal combustion engines. Lack of a direct means to initiate the combustion and high levels of Total Hydrocarbon (THC) and Carbon Monoxide (CO) emissions are major drawbacks associated with HCCI engines. Control of combustion phasing for optimum indicated thermal efficiency and minimizing emissions are vital for putting HCCI engines into practice. One major challenge is to develop accurate models for understanding engine performance, as those models can run real-time for HCCI control. This paper develops the first computationally efficient grey-box model for predicting major HCCI engine variables. The grey-box model consists of a combination of physical models and three feed-forward artificial neural networks models to estimate six major HCCI variables including combustion phasing, load, exhaust gas temperature, THC, CO, and NOx emissions. The grey-box model is experimentally validated over a large range of HCCI engines operation including 309 steady state and transient test conditions. The validation results show that the grey-box model is able to predict the HCCI engine outputs with average relative errors less than 10%. Performance of the grey-box methodology is tested for two different HCCI engines and the verification results show that the developed six-output grey-box model can be successfully used for performance modeling of different HCCI engine applications.

Investigations of the reduction of NO to N2 by reaction with Fe under fuel-rich and oxidative atmosphere

The limitation of nitrogen oxides (NOx) emissions from stationary combustion chambers is still an important issue in the field of the natural environment protection. This paper describes the reduction of NOx in the presence of iron. A few new aspects of research describing the utilization of iron as an additive that influences NOx reduction at high temperatures are presented. In particular, the influence of the excess air number (λ) on the NOx removal efficiency in the presence of Armco iron was determined. A >50 % increase in the efficiency was achieved at λ = 0.6. The research was conducted using N2/NO mixed with a flue gas from carbon monoxide combustion. In addition, a correction factor (Arrhenius-type empirical equation) was determined, which enabled the calculation of the oxygen influence on the inhibition of the de-NOx reaction in the presence of iron. The NOx reduction was also tested using bearing steel samples. Finally, the use of iron in de-NOx processes under different combustion conditions is briefly reviewed and analyzed.

OPERATING AND EMISSION CHARACTERSTICS OF A NOVEL DESIGN FOUR CHAMBERS INFECTIOUS MEAT INCINSRATOR

This paper investigates the operation and emission characteristics of a novel design four chambers inf ectious meat incinerator. This incinerator is internally divided into primary , secondary, intermediate and heat exchanger chambe rs. In the primary chamber, the infectious meat is burned using 95‐200 kW burner, the combustion products are then passed through the intermediate chamber, the secondary chamber, and ev entually through the heat exchanger chamber. A 50 kis installed in the secondary chamber to complete the combustion of CO and to destruct the dioxin. Fresh air is th en introduced to the flue gases to dilute the emission concentrations and to reduce the flue gas temperature. The flue gas is fi nally cleaned using an activated coke filter which is installed before the incinerator stack. The incinerator has been field tested at varied charging capacities of infectious meat, varied air to fuel r atios, and different combustion chamber temperature s. The emission concentration of particulate matter (P.M.), carbon monoxide (CO), sulfur dioxide (SO 2), nitrogen oxides (NO x,), heavy metals, and dioxin have been measured at the maximum chargi ng capacity of the incinerator. As a result of this work, it is proved that this incinerator offers an accepted and permanent soluti on to waste pollution problems that caused by infec tious meat. The measured emissions of this incinerator highly comply with th e maximum permitted emission limits of the environm ental law. The heat exchanger reduced the flue gas temperature to 160°C and increased the economic viability of the incine rator; about 50% of the fuel cost has been recovered by using the hot water in the slaughterhouse. Index Terms: Incineration, Slaughterhouse incinerators, Emissio n control by incineration.

Assessment of a transient homogeneous reactor through in situ adaptive tabulation

The development of computational models for the numerical simulation of chemically reacting flows operating in the turbulent regime requires the solution of partial differential equations that represent the balance of mass, linear momentum, chemical species, and energy. The chemical reactions of the model may involve detailed reaction mechanisms for the description of the physicochemical phenomena. One of the biggest challenges is the stiffness of the numerical simulation of these models and the nonlinear nature of species rate of reaction. This work presents a study of in situ adaptive tabulation (ISAT) technique, focusing on the accuracy, efficiency, and memory usage in the simulation of homogeneous stirred reactor models using simple and complex reaction mechanisms. The combustion of carbon monoxide with oxygen and methane with air mixtures are considered, using detailed reaction mechanisms with 4 and 53 species, 3 and 325 reactions, respectively. The results of these simulations indicate that the developed implementation of ISAT technique has a absolute global error smaller than 1 %. Moreover, ISAT technique provides gains, in terms of computational time, of up to 80% when compared with the direct integration of the full chemical kinetics. However, in terms of memory usage the present implementation of ISAT technique is found to be excessively demanding.

Preparation and characterization of phenolic foams with eco-friendly halogen-free flame retardant

The high solid resol phenolic resin was prepared via step polymerization of formaldehyde, paraformaldehyde, and phenol using sodium hydroxide and calcium oxide as catalysts, and employed to prepare the phenolic foams (PFs) by the introduction of retardant additives including eco-friendly halogen-free flame retardants (ammonium polyphosphate), char-forming agents (pentaerythritol), and synergists (zinc oxide, molybdenum trioxide, cuprous chloride, and stannous chloride). The effects of these additives on flame retardancy, heat resistance, and fire properties of flame-retardant composite phenolic foams (FRCPFs) were evaluated by limiting oxygen index (LOI) tests, thermogravimetric analyzer, and cone calorimeter tests. It was found that the flame retardan significantly increased the LOIs of FRCPFs. Compared with PF, heat release rate, total heat release, effective heat of combustion, production or yield of carbon monoxide (COP or COY), and Oxygen consumption (O2C) of FRCPFs all remarkably decreased. However specific extinction area and total smoke release significantly increased, which agreed with the gas-phase mechanism of the flame-retardant system. The results indicate that FRCPFs have excellent fire-retardant performance and less smoke release. APP/PER/ZnO is shown to be better flame-retardant system for PFs.

연소시 생성된 CO가스의 고찰을 통한 인명피해 최소화 방안에 관한 연구

Recently developed a variety of architectural interior decoration according hwadoeme type of toxic gases generated during fire also are becoming diversified, resulting in fatal casualties occurred in the trend is also being increased. During a fire, toxic gas that is generated varies depending on the combustible material occurs. However, all combustible materials, including carbon, incomplete combustion of carbon monoxide which is generated in the most common toxic gases can be seen as one. Accordingly, in this study of organic solids that are generated in case of fire toxic gases, and briefly discuss the characteristics of the risks and, by far the most common Co gas for measures to prevent human casualties, seolbijeok, the temperature dependence, divided into four aspects of administrative daechaekdeung explained.

High pressure kinetics of CH4, CO and H2 combustion over LaMnO3 catalyst

A high pressure kinetic study was carried out in a wide range of operating conditions to study the effects of pressure, temperature, fuel concentration and equivalence ratio on the catalytic combustion of methane, hydrogen and carbon monoxide over a perovskite-based catalyst. A plate type reactor configuration was chosen. This geometry allowed working in a kinetic control avoiding mass transfer limitations if appropriate experimental conditions are chosen. Since especially for GT application it is important to study the ignition phenomenon, which results to be ruled by kinetics, the study of the kinetics of CH4, H2 and CO catalytic combustion was carried out in a range of temperature consistent with the ignition temperatures and global reaction rate equations were derived.

Investigation on the thermal flame thickness for lean premixed combustion of low calorific H2/CO mixtures within porous inert media

The lean premixed combustion of hydrogen and carbon monoxide (H2/CO) mixtures within a porous inert media model-burner was investigated for ranges of H2/CO volumetric ratios from 2 to 4, inert volumetric concentrations in the fuel stream from 85% to 90%, thermal loads of 400kW/m2 (2kW) and 1000kW/m2 (5kW), constant reactants temperature of 673K and an equivalence ratio of ϕ=0.5. Experimental measurements and numerical predictions of temperature profiles and temperature gradients along the axial center-line of the combustion zone are presented and the thermal flame thickness is estimated and analyzed for the effect of thermal load, inert components in the fuel stream and H2/CO ratios. The adopted numerical model uses a volume-averaged approach and solves both the gas- and solid-phase energy balances explicitly and accounts for the radiative heat transport in the solid-phase. The thermal flame thickness results are compared with the respective laminar free flame values and differences between the flame thickness of free flames and flames inside a porous inert media are discussed.

Numerical Investigation of Radiation Effects in Monolithic Catalytic Combustion Reactors

In modeling catalytic combustion in a monolithic catalytic converter, it is generally assumed that the gas within the individual monolith channels does not interfere with thermal radiation. To date, no quantitative study has been undertaken to validate this assumption. Past studies for carbon monoxide combustion also appear to indicate that the emissivity of the washcoat has little effect on the thermal radiation field. In order to investigate these two issues, methane-air combustion on platinum is modeled inside a single channel of a monolith using a detailed surface reaction mechanism comprised of 24 reactions between 19 species. Radiation transport is modeled using the Discrete Ordinates Method and a gray formulation. Planck-mean absorption coefficients of the gases, calculated from the HITEMP and HITRAN databases, are used to investigate participating medium effects. All calculations were performed using the commercial CFD code, CFD-ACE+™, supplemented by user-subroutines for calculating the radiative properties of the gas mixture. Results show that the conversion percentages and temperature distributions are unaltered by the inclusion of participating medium radiation effects, verifying the commonly held belief, stated earlier. However, in strong contrast with carbon monoxide combustion, the emissivity of the washcoat was found to significantly affect flammability limits in the case of methane combustion—the flame being hotter and more stable for smaller values of emissivity.